Nucleotides

Nucleotides

Q. 1

Nucleotide is composed of:           

 A

Nucleobase + sugar

 B

Nucleobase + phosphate

 C

Nucleobase + sugar + phosphate

 D

Sugar + phosphate

Q. 1

Nucleotide is composed of:           

 A

Nucleobase + sugar

 B

Nucleobase + phosphate

 C

Nucleobase + sugar + phosphate

 D

Sugar + phosphate

Ans. C

Explanation:

 

Nucleotides

  • They are biological molecules that form the building blocks of nucleic acids (DNA and RNA) and serve to carry packets of energy within the cell (ATP).
  • In the form of the nucleoside triphosphates (ATP, GTP, CTP and UTP), nucleotides play central roles in metabolism.
  • In addition, nucleotides participate in cell signaling (cGMP and cAMP), and are incorporated into important cofactors of enzymatic reactions (e.g. coenzyme A, FAD, FMN, NAD, and NADP+)
  • A nucleotide is composed of a nucleobase (nitrogenous base), a five-carbon sugar (either ribose or 2-deoxyribose), and one or more phosphate groups.
  • Without the phosphate group, the nucleobase and sugar compose a nucleoside.
  • A nucleotide can thus also be called a nucleoside monophosphate.



Q. 2

Nucleoside is made up of

 A

Pyrimidine

 B

Sugar

 C

Purine

 D

All of the above

Q. 2

Nucleoside is made up of

 A

Pyrimidine

 B

Sugar

 C

Purine

 D

All of the above

Ans. D

Explanation:

Nitrogenous base + pentose sugar by covalent N- glycosidic bond.


Q. 3

First carbon of pentose sugar of nucleic acid joins

 A

N-9 of pyrimidine

 B

N-1of pyrimidine

 C

N-1 of purine

 D

None of the above

Q. 3

First carbon of pentose sugar of nucleic acid joins

 A

N-9 of pyrimidine

 B

N-1of pyrimidine

 C

N-1 of purine

 D

None of the above

Ans. B

Explanation:

Pentose sugar present in DNAs is deoxyribose and in RNAs it is ribose. A pentose sugar (ribose or deoxyribose) is linked to a nitrogenous base (purine or pyrimidine) via covalent N-glycosidic bond to form nucleoside. This linkage joins the Carbon-I of pentose sugar with nitrogen-9 of the purine base or nitrogen-I of pyrimidine base.


Q. 4

Which of the following is a nucleotide?

 A

Adenine

 B

Uridine

 C

Thymine

 D

Guanine

Q. 4

Which of the following is a nucleotide?

 A

Adenine

 B

Uridine

 C

Thymine

 D

Guanine

Ans. B

Explanation:

Nitrogenous

Base

Pentose Sugar

Nucleoside

Nucleotide

Adenine

Ribose

Adenosine

Adenosine Monophosphate (AMP)

Guanine

Ribose

Guanosine

Guanosine Monophosphate (GMP)

Uracil

Ribose

Uridine

Uridine Monophosphate (UMP)

 

 



Leave a Reply

%d bloggers like this:
Malcare WordPress Security